Importance:
Quadrant streaking is an important technique to use is microbiology. This technique is used to isolate colonies from a mixed population of microorganisms. Having isolated colonies shows a single group of bacteria with the same genetic material, this is known as a "pure culture". This will show what the bacteria is causing the disease and this will allow scientist to be able to study this line of bacteria more in depth.
Scientist can use the isolated colonies to study characteristics of a particular microbe. Scientist can do this by gram staining the sample or putting the sample through biochemical testing. The scientist will also be able to take the isolated colony from the quadrant streak and test it against other bacteria to see how it will react!
Normally to Prepare an Agar Plate You Would:
Autoclave the nutrient agar media at 121 degrees Celsius for 20 minutes
Pour the nutrient agar media into the plate and allow it to solidify
Most of the time you can buy pre-made plates with the agar media already in the plate, and solidified.
Streaking Methods:
Sterilize the inoculating loop over the bunsen burning until it becomes red hot, let the loop cool for 20-30 seconds so that when the loop touches the bacteria it won't fry the bacteria
2. Take the sterilized loop and scoop a small sample from the original sample and streak the sample in the 1st quadrant in a zig-zag motion across the quadrant then close the lid to limit contamination. (Look at number 1 on the figure to the left to get a good visual.)
3. Sterilize the loop in the bunsen burner until red hot and let cool
4. Lightly drag the loop back and forth on the 2nd quadrant intersection the 1st quadrant 2 or 3 times and close the lid. (Look at number 2 on the figure to the left to get a good visual.)
5. Sterilize the loop in the bunsen burning until red hot and let cool
6. Lightly drag the loop from the beginning of the 2nd streak into the 3rd quadrant and close the lid. (Look at number 3 in the figure above to get a good visual.)
7. Sterilize the loop until red hot and let cool
8. Lightly drag the loop from the 3rd streak into the 4th quadrant and extend up the middle of the plate and close the lid. (Look at number 4 in the figure above to get a good visual.)
9. Sterilize the loop for the last time before putting it away
10. Incubate the plat at the desired temperature and time and observe results!
If you want to know more about quadrant streaking or want a better visual, please check out this great video which shows a great example of how to quadrant streak properly!
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